Research Of Residual Stresses In Plates During The Straightening Process

The advanced steel production process reflects a country's comprehensive national strength,with the completion of China's comprehensive completion of the century-old goal of a well-off society,steel plays a key role,the construction of modern cities is inseparable from steel products,the development of more than90% of domestic industries are inseparable from the support of steel,steel plate as steel products,the most widely used products,with its application range in As a steel product,the most widely used product,with its application range is expanding,the user requirements for the quality of steel plate is also increasing.The quality of the plate is mainly reflected in the straightness and residual stress of the plate.As the last production process in the production line,the straightening machine can ensure the accuracy of straightness,reduce the residual stress and improve the production efficiency.However,the straightening process of steel plates is an elastic-plastic bending process with alternate loading and unloading,and it is very difficult to analyze the straightening process accurately.This paper considers the method of numerical calculation of stresses in the straightening process in the initial residual stress state.(1)Using the curvature integral straightening mathematical model,the model is solved numerically using an iterative approximation method.Based on this,the straightening process is analyzed considering the equipment bounce and a process optimization method is established.The calculation results show that as the straightening proceeds,the influence of the bounce factor gradually increases during the nibbling process,smooths out during the continuous straightening process,and gradually decreases during the final tailing stage.In addition,as the plate thickness increases,the variation of bounce on the straightening process parameters increases.(2)Using the elastic-plastic mechanics and the straightening principles,the change in residual stress during the straightening process of the plate considering the initial residual stress state was analyzed analytically,and a numerical calculation method was established.The calculation results show that the roll straightening process is an effective method to reduce the residual stresses.Before straightening,the x-and z-directions of the upper and lower surfaces were at compressive stresses of about-276 MPa,and after straightening,the residual stresses on the upper surface were reduced to 42-79 MPa in the x-direction and-89-122 MPa in the z-direction.on the lower surface,the x-direction was reduced to-56-115 MPa and the z-direction was reduced to 23-58 MPa.(3)Using MSC.MARC finite element analysis software,finite element simulation models for quenching and continuous process straightening were established,and the deviations of the three-way residual stresses in the longitudinal section were obtained by comparing the numerical solutions with the experimental results;and the deviations from the calculation of the analytical model were within 15% by using the experimental field data of the total one-way straightening force and the tests of the residual stresses on the surface after quenching and after straightening.The accuracy of the numerical model for the quenched and continuous process straightening residual stresses was further verified.